The present invention relates to a transmission circuit, a data transfer control device and electronic equipment.
As a data transfer control which uses deferential signals, Universal Serial Bus (USB) standard is known as an interface standard which couples, for example, a personal computer and its peripheral devices. As a demand for a faster data transfer has been recently increased, products that conform to or are compatible with High Speed newly defined in USB 2.0 standard. The USB standard 2.0 can transfer data faster than Low Speed and Full Speed defined in USB 1.1 standard. A data transfer control device and the like that conform to the High Speed newly defined of the USB 2.0 standard are variously designed to perform an appropriate data transfer (see Patent Document 1).
As for the Low Speed and the Full Speed defined in the USB 1.1 standard or the USB 2.0 standard, for example, even if a device controller that sends data or a host controller is not exactly made to conform to the USB 1.1 standard, the host controller can often properly receive or transfer data because a data transfer rate is low. Therefore, few problems occur when the data transfer in the Low Speed and the Full Speed defined in the USB 1.1 standard or the USB 2.0 standard is performed with the products that do not exactly follow designing requirements of the USB 1.1 standard.
However, as for the High Speed newly defined in the USB 2.0 standard, when a device which sends data to a receiving circuit of the host controller that receives data is not made so as to conform to designing requirements of the USB 2.0 standard, the data could not sometimes be transferred properly even if the transmitted data waveform is complied with the standard. This is because a theoretical value of the data transfer rate of the High Speed is 480 Mbps, which is very fast. Nevertheless, such products that do not exactly follow the designing requirements of the USB 2.0 standard exist in the market.
For example, when the host controller that receives data is not made so as to follow the designing requirements defined in the standard, even if the device controller is made to properly conforms to the designing requirements and sends a signal having a wave form that complies with the standard, the data transfer could not be properly performed sometimes.
Correspondingly, when the device controller that receives data is not made so as to follow the designing requirements defined in the standard, even if the host controller is made so as to properly conforms to the designing requirements and sends a signal having a wave form that comply with the standard, the data transfer could not be properly performed sometimes.
[Patent Document 1] Japanese Unexamined Patent Publication No. 2002-344542.
The present invention has been developed in consideration of the above-mentioned problems, and intended to provide a transmission circuit which can adequately perform a fast data transmission even to a host controller and a device controller which are not made to exactly follow designing requirements defined by standards. The present invention is also intended to provide a data transfer control device and electronic equipment.